Low cycle fatigue testing can be used to evaluate the fatigue performance of small diameter tube butt welds at high stress range, high strain deformation, and low cycle numbers. It is commonly used for testing the fatigue properties of tubing welds present in the subsea control system. For example, during steel tube umbilical fabrication, the umbilical may experience large deformation when it passes through a radius controller, or stored on a reel. Such large deformation can be beyond the steel yield range, when the steel tube will go beyond the elastic deformation region, and experience certain degree of plastic deformation, which will not reverse, and thereby cause permanent elongation in the tube, and generate significant fatigue damage to the tube, which is called low cycle fatigue. Welds and connection joints are usually the weakest point for low cycle fatigue. During the test, the tube-shaped testing specimen is bent to the desired radius, and the smaller the radius, the higher the strain and stress, which sometimes can be beyond the yield stress. Next the tube-shaped testing specimen is straightened out to complete one cycle. After repeating this bending-straightening process for a certain number of cycles, the specimen will experience fatigue crack and fail eventually. Conventional testing method uses a pre-fabricated disc or cylinder, each with a defined radius, to bend the tube into the desired radius, then straighten the bent tube through a tube straightener or tension pull, which can be time-consuming, and sometimes produces biased testing results by introducing excessive tension loads. During steel tube umbilical fabrication, the steel tube usually bends into one direction first, and then bends into the opposite direction in the following cycle, which is not reflected in the conventional testing method. Apparatus and methods have been proposed for performing low cycle fatigue testing, which, among other applications, can be used for testing the fatigue performance of the umbilical (or steel tube bundle), which can experience low cycle fatigue during the fabrication process.